In many transmission systems, transmitting and receiving devices interact to establish parameters associated with communicating between themselves. For example, in a discrete multitone (DMT) system, the transmitting and receiving devices exchange information to establish communications parameters during a period referred to as a training period. The training period typically includes a handshaking process in which the devices learn about each others capabilities, indicate the protocol to be used for transmission between the two devices, identify the number of carriers or tones to be used to carry data, etc.
After the handshaking, the devices perform a channel analysis to identify the condition of the channel over which data will be transmitted. The devices may also perform timing analysis/timing recovery to synchronize the transmitter and receiver, adjust receiver gain and perform other steps to ensure that the two devices are able to communicate.
One problem associated with the training period is that the data transmitted between the two devices may be subject to noise, intersymbol interference (ISI) and intercarrier interference (ICI). In addition, various channel qualities are also unknown during training, such as the channel frequency response. As a result, a receiving device may be unable to correctly decode a transmission associated with setting up the parameters for communicating with a transmitting device. This may lead to a training failure and result in the two devices being unable to establish communications with each other.